Children with cardiomyopathy represent the most dismal outcome of any group of diseases followed by pediatric cardiologists, with up to 40% of infants and children with symptomatic cardiomyopathy failing medical or surgical management in the first year following diagnosis. For 57% of children with cardiomyopathy, no etiology is known. Although pediatric cardiomyopathy is common, there is considerable variation in its causes. Therefore, for any specific etiology, no center of pediatric cardiology sees a sufficient number of patients to make major advances in understanding this group of diseases. For these reasons, the overall aim of this proposal is to establish and maintain a national registry for children with different forms of cardiomyopathy in order to collect and organize all relevant clinical and demographic information. Data accrued by and reported by the registry should lead to increased awareness and knowledge of pediatric cardiomyopathy and its causes, as well as the development of new diagnostic and therapeutic approaches. Specific hypotheses are that l) during the period of the registry, the percentage of cases that are diagnosed as idiopathic will decrease (i.e., etiologies will be found) and 2) at the time of diagnosis of cardiomyopathy, factors such as gender, ethnicity, age, type of cardiomyopathy, and presence or absence of a syndrome can help predict outcomes. The proposed Pediatric Cardiomyopathy Registry will consist of a national data coordinating center at the New England Research Institute and an administrative core and clinical quality assurance center at Children's Hospital in Boston. Definition of entry and exclusion criteria, clinical quality assurance, and accrual and retention of participating clinical centers will be largely under the direction of Children's Hospital in Boston and Baylor College of Medicine. Virtually all pediatric cardiology centers in the United States, Puerto Rico, and Canada have expressed their willingness to send patient information to such a registry. This disease-specific coordinated network should foster genetic studies in this area among many investigators by providing the infrastructure and ways to interact. Many of the important mutations causing human disease are predicted to be identified during the next 10-20 years; formation of the Pediatric Cardiomyopathy Registry will enhance the likelihood that this will happen. The registry should lead to definitive understanding of the pathogenesis of these disorders and offer the hope to have a major clinical impact on the clinical practice of medicine in this area.